Filaments and/or fibers comprising a filament-forming material and an additive, such as a surfactant, a perfume, a filler, and/or other ingredient, are known in the art. For example, nonwoven fabrics comprising fibers made from an aqueous solution comprising 5-95 wt % pullulan and 50 wt % or less based on the pullulan of a perfume (an active agent) that slowly releases (“blooms”) from the fiber while the fiber's morphology does not change during use are known in the art and are used as sanitary products. The aqueous solution used to make the pullulan fibers further comprises 15 wt % or less based on the pullulan of a surfactant that functions as a processing aid, which does not release from the fiber until the fiber undergoes natural decomposition after its use.
Fibers comprising polyvinyl alcohol and/or a polysaccharide and significantly less than 5% by weight of active agents, wherein the active agents release from the fibers while the fibers maintain their fiber properties during use are also known.
A cigarette filter made from electrospun fibers comprising a polysaccharide and 10% or less by weight of an active agent, such as a flavorant, that releases from the fibers as the fibers dissolve after being contacted with moist air is also known in the art.
In addition, fibers made from a non-aqueous solution formed by melting a synthetic wax and adding a primary surfactant and a secondary surfactant to the melted synthetic wax and then cooling the synthetic wax/surfactant mixture such that fibers are formed are known in the art.
Further, fibers and/or filaments that comprise processing aids, such as surfactants, and/or fillers are also known. Such processing aids and/or fillers are not designed to be released from the fibers and/or filaments when the fibers and/or filaments are exposed to conditions of intended use. Further, the total level of the processing aids within the fibers and/or filaments is significantly less than 35% by weight on a dry filament basis and the total level of fillers present in the fibers and/or filaments is typically less than 45% by weight on a dry filament basis.
From the known examples described above, it is clear that the previously existing knowledge suggested that the total level of filament-forming materials needed to exceed the total level of additives, especially active agents, in order for the filament to exhibit a filament structure.
As is evident from the above discussion, known fibers and/or filaments contain less than 50% by weight on a dry fiber/filament basis of active agents that may released from the fibers and/or filaments when exposed to conditions of intended use.
In addition to the known fibers and/or filaments, there are known foams that comprise a foam-forming polymer, such as polyvinylalcohol, and an active agent, such as a surfactant. Such foams do not contain filaments and/or fibers and/or are not nonwoven substrates containing such filaments and/or fibers.
Lastly, as shown in prior art FIGS. 1 and 2, there are known nonwoven substrates 10 that are made of dissolvable fibers 12 wherein the nonwoven substrates 10 are coated and/or impregnated with an additive 14, such as a skin care benefit agent, rather than the additive 14 being present in the dissolvable fibers 12.
As can be seen from the state of the art, there exists a need for a filament and/or fiber that comprises one or more filament-forming materials and one or more active agents that are releasable from the filament, such as when exposed to conditions of intended use and/or when the filament's morphology changes, wherein the total level of the one or more filament-forming materials present in the filament is 50% or less by weight on a dry filament basis and the total level of the one or more active agents present in the filament is 50% or greater by weight on a dry filament basis. Such a filament would be suitable for carrying and/or delivering the active agents in various applications. Further, there is a desire to produce a filament that has a greater level of additive, for example an active agent, than the filament-forming material, for example a polymer in order to optimize the delivery of the active agent with minimal cost and a relatively faster rate of delivery compared to filaments that have a greater level of filament-forming material than active agent.
It is also desirable to incorporate active agents into filaments that otherwise are incompatible with carrier substrates. The present invention also allows normally incompatible active agents to be incorporated into the filament, either into the same filament and/or into different filaments within a nonwoven web comprising the different filaments.
Accordingly, there exists a need for a method for delivering active agents and for novel filaments that comprise a filament-forming material and an active agent that is releasable from the filament and/or fiber and/or from a nonwoven web made from filaments and/or fibers, and/or a film made from filaments and/or a nonwoven web.